This invention is concerned with an apparatus and method for improving the characteristics of waxy material, particularly wax-based stick applicators.
Many cosmetic and personal care items such as lipsticks, deodorants and anti-perspirants are produced in so-called stick form, which stick comprises a substantial quantity of low melting waxy material and substances to be applied to the surface of the body, e.g. essential oils and perfumes. Such sticks are sold in cylindrical containers and can be elevated above the container level for application to the body and then lowered again. One such cylindrical container has a hollow shell in which is mounted an externally threaded shaft. The shaft extends through the bottom of the hollow shell where it is connected to a rotatable base. A shallow dish having an internally threaded central aperture is placed on the shaft at the bottom of the hollow portion. The container is filled by introducing a liquid formulation of the product into the hollow shell at an elevated temperature. Thereafter, the formulation is allowed to cool and solidify. The solidified wax-based product rests on the shallow dish and as the base is rotated, the dish is threaded upwardly on the shaft and the stick carried by it is raised to a level sufficient for application.
In order to make the product more appealing to the consumer it is desirable that the surface of the waxy material be smooth and uniform and throughout its service life and initially substantially level.
Unfortunately, after filling the containers with the liquid formulation and allowing solidification, the solidified the stick very often contains small air-entrapped bubbles and a central hollow nodule formed as a consequence of the solidification of waxy material above and around the central shaft. The waxy material also adheres to the top inside surface of the container above the level of the bulk of the material thus creating an undesired meniscus. Such air spaces appear as the stick is used up and create an undesirable product. It is an object of the present invention to provide an apparatus and method for significantly improving the characteristics of waxy material by removing undesirable imperfections.
It is an object of the invention to provide an apparatus and process in which waxy material is sequentially melted and resolidified a number of times under controlled pressure conditions thereby smoothing the surface and eliminating any bubbles and nodules from the composition and the adherence of the waxy material to the sides of the container.